This invention relates to the field of tubing clamps such as the clamps used to secure the components of internal combustion engine exhaust systems.
Exhaust system components are generally connected by sliding a pipe segment of smaller diameter (such as a segment attached to a muffler) into the end of an exhaust pipe and tightening a clamp on the overlapping portions of pipe. Several problems have been associated with the prior-art clamps used to connect exhaust system components, including problems of adequate joint sealing, and problems in installing and removing the clamps when an exhaust system component is to be replaced.
It is important that clamps used to connect the pipes seal the joint completely to prevent escape of poisonous exhaust gases and objectionable exhaust noise. To accomplish this objective, some clamp designers have designed clamps that beform both the inner and outer pipes around their entire circumference to interlock the pipes. A clamp of this type is described in U.S. Pat. No. 4,388,749 to Sassak. The single. blunt deforming edge used in this type of clamp may not seal the joint adequately in cases where the inner and outer pipes do not mate perfectly.
U.S. Pat. No. 2,719,345 to Riker shows a tubing clamp having a single sharp edge abutting a portion of the outer pipe. This sharp edge compresses the outer pipe and appears to produce a more pronounced interlocking than goes a blunt edge. Nevertheless, clamps of this type may not be adequate to seal the joint since the sharp edge does not continue around the circumference of the pipe. A novel and unique clamp with a plurality of sharp edges continuing around the circumference of the pipe which form a series of pronounced seals between the inner and outer pipes would offer a significant advantage.
There have also been problems in installing and removing prior-art clamps. These clamps generally have a circular section around the pipes, and the nuts for tightening the clamp mount on threads lying in a line tangential to the circumference of the outer pipe. Thus, tightening of the nuts creates a torquing force about the central axis of the joined pipes, tending to cause rotation of the clamp about the said central axis during tightening. A novel and unique clamp with a modified circular section around the pipes, and also having nuts that can be tightened first by hand and then by using a wrench, would offer a significant advantage.
Removing prior clamps is difficult because prior art clamps have generally been constructed of ordinary steel. When mounted under a motor vehicle, these clamps quickly corrode so that they cannot be removed except with a cutting torch. These cutting operations are dangerous because the hot torch flame must be used in the area of the gas tank and greased chassis parts. There is also a constant risk of injury to the operator inherent in using a torch, while the heat will damage metal parts of the vehicle. Applying extreme heat to the exhaust pipes and/or the underbody of the vehicle will harden these metal parts, making them brittle. This heat will cause particular damage to the stainless steel exhaust pipes which are standard equipment on many vehicles. If the parts involved are galvanized to prevent corrosion, extreme heat may destroy the effectiveness of the galvanitic treatment and lead to premature failure of the metal. Thus, there is a need for a tubing clamp which can be removed from the exhaust system of a vehicle without cutting operations.